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Pool 13 drawdown: Predicting success rates and affected areas

April 1, 1999

The likelihood of 1- or 2-foot drawdowns, and the area affected by such alternative drawdowns, was estimated for Pool 13 on the Upper Mississippi River. Minimum water surface (elevation) requirements were compared to computed water surface profiles to determine a critical low flow that would allow a navigation channel 400 feet wide and 10.5 feet deep. An upper limit on flow was established based on the flow at which open river conditions would exist for a given drawdown. The range in flows that would allow for a drawdown was used to estimate success rates using historical daily discharge data. Success rates were determined for a variety of drawdown durations between two time periods. May 1—August 15 and June 15—August 15. The greatest effect of the drawdown would he near Lock and Dam 13. Higher discharges, as well as distance from the dam. lessen the drawdown amount. Areas that would he affected by these two drawdown scenarios were predicted by overlaying maps of water surfaces with depths using a geographic information system. Although the drawdown effects on most physical and biotic components of Pool 13 arc unknown, some general drawdown effects likely to occur because of the changes in water surface elevation are presented.

Publication Year 1999
Title Pool 13 drawdown: Predicting success rates and affected areas
Authors James T. Rogala, Joseph H. Wlosinski, Kevin J. Landwehr
Publication Type Report
Publication Subtype Federal Government Series
Series Title Long Term Resource Monitoring Program Technical Report
Series Number 99-T002
Index ID 70210547
Record Source USGS Publications Warehouse
USGS Organization Upper Midwest Environmental Sciences Center